linux-kernel - Re: [PATCH-tip v5 17/21] TP-futex: Group readers together in wait queue

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Message-ID: <18211.1486150017@turing-police.cc.vt.edu>
Date:   Fri, 03 Feb 2017 14:26:57 -0500
From:   valdis.kletnieks@...edu
To:     Waiman Long <longman@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Mike Galbraith <umgwanakikbuti@...il.com>,
        Scott J Norton <scott.norton@....com>
Subject: Re: [PATCH-tip v5 17/21] TP-futex: Group readers together in wait queue

On Fri, 03 Feb 2017 13:42:46 -0500, Waiman Long said:

> This patch set does guarantee some minimum performance level, but it
> can't guarantee fairness for all the lock waiters.

OK, sounds like it's a situation that's statistically unlikely, but it has
protections against starvation so the system will eventually dig itself out of
the hole, and the scenario is at least known and understood.  The improved
numbers for average-case probably outweigh the worst-case then...


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